From the motion of the spots, which is sometimes straight and sometimes curved, we learn that the sun’s axis is not perpendicular to the plane of his ecliptic, but inclined to it, or the plane of the earth’s annual orbit, so as to form an angle of about 83 degrees. Christopher Scheiner, a most diligent observer of these spot’s in the sun’s disk, published a treatise concerning them in A.D. 1626. These spots are sometimes seen to increase to a very large size, and to continue for a considerable time. In the year 1779, there was a spot on the sun’s disk which was large enough to be seen with the naked eye: it was divided into two parts, and must have been 50,000 miles in diameter: this, and other phenomena of the same kind, may be accounted for from some natural change of the atmosphere. For if some of the fluids which enter into its composition be of a shining brilliancy, while others are merely transparent, then any temporary cause removing the lucid fluid, will permit us to see the body of the sun through the transparent ones. Dr. Herschell supposes that the spots in the sun are mountains on its surface, which, considering the great attraction exerted by this luminary upon bodies placed at its surface, and the slow revolution it has about its axis, he thinks may be more than 300 miles in height, and yet not be rendered unstable by the centrifugal force. [There appears to be a _discrepancy_ between this last statement--“Dr. Herschell supposes that the spots in the sun are _mountains_ on his surface;”--and the statement made a few paragraphs preceding--“that what are called _maculæ_, or _spots_ on the sun, Dr. Herschell thought to be _real openings_ in his atmosphere, through which the opake body of the sun becomes visible.” These statements must have been made at different periods of his observations on the sun, which continued about fifteen years. The last statement was, doubtless, Dr. Herschell’s mature opinion. As this seems to be a settled question among philosophers; and as it has induced the enlightened world to regard the sun as a _habitable globe_, it will not be out of place to enlarge a little on this point. The spots on the sun’s surface has led to the conclusion above, and also to a determination of the motion of the sun around his own axis. They appear to have been observed, for the first time, in A.D. 1610, by Fabricius and Harriot; the first in Germany, the second in England. It is uncertain which noticed them first; but it is certain the discovery was _original with both_.